Conventional optical scanners employ linear array optical sensors, and an apparatus for providing relative motion between the document or image to be scanned and the linear array sensor. In a general sense, the image is scanned by producing a series of scans of a given swath width, which are then assembled or processed by a processor in a rectilinear, Cartesian sense to provide the scanned data representing the image or document.
This invention improves upon the typical, rectilinear Cartesian document scan in such a way as to produce sampled information from printed, drawn or photographic media which exactly matches a method of ink-jet printing along a spiral path locus. This invention also provides a way to capture the information present on the media all the way to the edges of the scanned media the same as in flat-bed scanners, and results in a simpler mechanical structure for the scanner.
In the referenced co-pending application Ser. No. 09/066,621, entitled "Inkjet Printing Techniques Using Spiral Relative Motion Between the Print Medium and Printing Elements," a method is describer which improves upon an ink-jet printing hysteresis problem, and an ink-jet printing margin problem. In this co-pending application, it is shown that, by printing in a uni-directional manner along a spiral path, both of these printing problems are reduced or eliminated. However, because document scanners typically scan information from text or photographic media in a raster or x-y Cartesian fashion, there then necessitates a re-sampling or conversion from rectangular coordinates to polar coordinates to effect the printing of the scanned data on a spiral path. It is realized that this conversion process could produce undesirable printing artifacts under some circumstances, and the purpose of this invention is to eliminate these artifacts entirely. Also, in many non-flatbed scanners, mechanical constraints do not allow the scanning sensors to view documents all the way to the document edges; hence information may be lost during a conventional non-flatbed scanning process. This invention also can result in a simplification of the mechanism required to move and house the scanner, since the scanning array may be mounted either in place of, or radially co-linear with, an ink-jet printing nozzle array, thus providing a printer and a scanner, both of which share electrical and mechanical parts to a large extent.